Fertility Results in Beef Cattle: Insemination v. Embryo Transfer

This thesis focuses on the fertility and fertility results in a monitored breeding herd of Limousin beef cattle. It includes a brief discussion of calf birth weights, their viability, and the time of calving. Taking this information into account, the main objective of this thesis is to present concise and accurate information regarding the age of purebred and crossbred heifers when they are first included in the reproduction process. The thesis also aims to evaluate the pregnancy success rates for insemination, embryo transfer, and natural breeding. Finally, the thesis tracks the calving difficulties experienced by cows and heifers after artificial reproduction methods and natural breeding. The conclusion includes calf birth weight figures and identifies the weight difference between newborn bulls and heifers. The results were evaluated using basic statistical characteristics. The collected data was analyzed according to the breeding method used and taking into account whether a cow or a heifer was involved. The age of purebred heifers during their first breeding is 26.1 months. The age of crossbred heifers included in the reproduction process as embryo recipients was 22.6 months. In the case of natural breeding, the crossbred heifers were first included at the age of 28 months due to the seasonality of the breeding season. The pregnancy success rate for first breeding by insemination is comparable to that for embryo transfer 62% and 63% respectively; in the case of natural breeding, the success rate is 92%. The highest number of easy births was determined for natural breeding (95%), followed by insemination (89%), and embryo transfer (only 61%). The birth weight of heifers was 2 kg less than that of bulls, and thus the number of easy births was higher. The average birth weight in 2014 was 41 kg. The top calving time was between midnight and 4:00 am (30% of the breeding cows)